Johnson asked why the people who were evacuated safely weren't interviewed immediately. He said that he believed U.N. Ambassador Susan Rice "intentionally misled" people in the initial aftermath of the attack by blaming it on a spontaneous protest, a charge that Clinton brushed off and said "nothing could be further from the truth."

When Johnson continued to press her on the initial misleading information, Clinton got visibly animated and shouted down Johnson before he could finish his question.

"We had four dead Americans!" she said. "Whether it was attack preplanned by terrorists or it because of a guy out for a walk one night who decided they'd go kill Americans ... What difference does it make?!"

Clinton's testimony comes after months of Republican charges that the Obama administration misled by originally blaming the attack on a spontaneous protest sparked by an anti-Muslim video. Republicans charge that the administration ignored warning signs of an increasingly bleak situation in Libya and failed to beef up security.

In her testimony, Clinton defended her handling of the lead-up to the attack and its aftermath but said that she accepted responsibility.

Clinton said she was not responsible for changing talking points that led to immediate confusion over whether the attack was carried out by terrorists.

"I personally was not focused on talking points. I was focused on keeping our people safe," Clinton said.

UPDATE: Johnson reacted to the exchange afterward with Wisconsin radio host Charlie Sykes. During his interview with Sykes, he accused Clinton of engaging in "theatrics" instead of providing a simple answer.

"I wasn't trying to get under her skin," Johnson told Sykes. "I was trying to get a relatively simple question answered that she didn't want to answer."

"It was theatrics,” he added. "Again, she didn’t want to answer questions so she makes a big show of it."